The best hypoallergenic diet includes proteins and carbohydrates that your cat has never had before, since most food allergies develop from exposure to certain ingredients. Hypoallergenic cat foods make use of uncommon sources of protein that are not usually incorporated into cat food. Many hypoallergenic cat foods contain rabbit, duck, lamb or venison, as a source of protein, since most cat food formulas contain chicken, beef, eggs or fish.
In many cases, it's very difficult to figure out the specific cause of your cat's food allergy. You may have to try several different formulas until you find one that works for your cat. In addition to this, many food allergies manifest as skin problems in your cat, not necessarily including gastrointestinal symptoms (such as diarrhea). This causes the mis-treatment of the condition, as this is also a symptom of sarcoptic mange, seasonal skin irritation, and other skin-related conditions. Many people will not immediately suspect food allergies to be the cause of their cat's skin problem.
When switching to a hypoallergenic cat food, it's important to choose carefully in the best type of food to incorporate into your cat's diet. A drastic change in food (especially if the new food has a higher carbohydrate content) may further upset your cat's digestive system.
The best way to test your cat's tolerance for a hypoallergenic cat food is to feed your cat the hypoallergenic food for approximately two weeks. After this two week period, switch back to your cat's original cat food. Be sure to keep an eye on your cat's condition! If they symptoms lessen with the hypoallergenic food, switch back to that type of food permanently. If not, try a different hypoallergenic cat food formula. You can also try testing to see if your cat is allergic to products such as dairy, soybeans, and certain food additives. This is a very involved process, and requires keeping constant surveillance over how your cat adapts to each new diet. Be sure to stick to the chosen diet (dairy-free, fish-free, egg-free, etc.) for the full two-week period, without any supplemental treats or additional food items. This is very important, since it will greatly help you in finding the right type of hypoallergenic cat food that is best for your cat.
In addition to a specific protein intolerance (chicken, beef, fish, etc) it's also possible for your cat to become allergic to certain types of carbohydrates. Remember, your cat is classified as an obligate carnivore, and requires a highly meat-based diet in order to be in optimal health. Try switching to a food that has between a 5-10% carbohydrate content, and see if your cat responds to this type of diet. If this doesn't work, you can also try eliminating specific carbohydrates, instead opting for uncommon carbohydrates such as potatoes, peas, and sweet potatoes.
When choosing a hypoallergenic cat food, reading the ingredients of the cat food formula becomes all the more important! Some possible allergens can have many different forms, so it's best to thoroughly research the type of hypoallergenic food to feed your cat.